A number of known label decoration technologies are available and each of them possesses various advantages and disadvantages.
Self-adhesive or pressure-sensitive labels are well-known and widely used in the industry. They suffer, however, from a number of disadvantages which include the fact that the production process is rather complex. Firstly a release liner is coated on one side with a release agent, typically silicone, and then on top of this cured silicone layer, a layer of pressure-sensitive tacky adhesive is applied which remains tacky for unlimited time throughout the lifetime of the product. A paper or filmic print-carrier is then laminated to the adhesive coated release liner, at which point the adhesive is preferably transferred to the print carrier. Rolls of such a pressure-sensitive laminate are then supplied for printing the face-side and die-cutting the labels to the required shape and finally removing the waste matrix of the face side. The labels are then ready to be applied to the item to be labelled and at this point the removable liner becomes a waste product which is a major disposal issue for users of such labels and the industry at large as well as the whole environment.
Another known alternative is the use of wet-glue labels in which pre-printed and die-cut paper labels are coated with a wet-adhesive and applied to the substrate. Typically, such wet-glue label operations are very messy with a large amount of time being lost for clean-up, set-up and changing of label formats. In addition, such wet-glue labels almost always exhibit the unattractive gripper marks of the “label-box” on the finished labelled object (The label-box is a device which holds the paper labels prior to the application of the adhesive and their application to a surface.). Furthermore, wet-glue labels are not available with clear films due to the technical problem that the water cannot evaporate and escape from such labels in a completely satisfactory manner resulting in unattractive bubbles in the label.
Another decoration technology is that of shrink-sleeves, in which case the total applied cost is very high and the production process is complex. Shrink-sleeve films are normally printed on wide-web gravure or flexographic presses with solvent-based inks, which could be an environmental and safety hazard. After printing, in a separate offline process the film is formed into a tube and the seams are adhered together by the use of a solvent welding process. This tube is then cut into shorter lengths, dropped over the article to be labelled which is then fed through a shrink-tunnel at high temperature causing the film to shrink and fit the shape of the container. Although this technology has produced a number of eye-catching and appealing results for some target market segments, it has a number of disadvantages. These include the fact that by definition a shrink-sleeve covers the whole surface of the object to be labelled and therefore 180° decoration or a label covering only part of the container surface is not possible. The visibility of unattractive seams on shrink-sleeve labels is also a negative issue. It is not possible to use shrink-sleeves for containers with flat sides or with containers with handles. It is not possible to use paper labels with shrink-sleeves nor it is possible to have a variety of textures or tactile effects. It is also not possible to have spot labels, multiple labels on a container or unique label shapes when using shrink-sleeves. Neither is it possible to achieve the so-called “No-label” look with shrink-sleeves, that is, it is not possible to have the label blend with the container colour and material as if the label was not there and that the container was pre-printed.
Another widely-used label technology is that of wrap-around labels. Wrap-around labels can be produced from either paper or film and can be fed from stationary magazines or directly from reels. Typically a hot-melt adhesive is applied to the leading edge of the label which is tightly wrapped around the container being rotated at a controlled speed, with the trailing edge being fixed in place by a second narrow strip of hot-melt adhesive. The major markets for such labels are soft drinks and mineral waters due to the lack of premium look and therefore the marketing appeal of the labels. It is not possible in this case to achieve the “No-label” look. The choice of materials is very limited and design variety is restricted to that of simple cylindrical shapes.
Publication US 2007/0014985 discloses compositions having a structured morphology. When triggered or activated by a suitable action, the morphology changes, causing a corresponding predetermined change in the property of the composition. Examples range from non-tacky to tacky, from uncured to cured, including change in colour, change in intensity of presence of fragrance, odor or smell, ranging from non-reactive to reactive and from stable to non-stable. The publication discloses also non-tacky films which become tacky in consequence of heating. Such activation by heating thus results in change of the tackiness of the film, but this tackiness is preserved upon cooling and the end result is similar to a pressure sensitive adhesive that remains tacky for unlimited time.